IDT Tsi578, Руководство пользователя

Страница: 72 / 527

3. Serial RapidIO Electrical Interface > Port Power Down 72
Tsi578 User Manual
June 6, 2016
Integrated Device Technology
www.idt.com
If port 0 requires a different speed from the default speed, two I
2
C EEPROM entries are necessary
because port 0 does not have a power down configuration pin. In this case, the first I
2
C EEPROM entry
for SMAC0_DLOOP_CLK_SEL must power down the port (SMAC0_DLOOP_CLK_SEL =
0xXXXXXXXC). The second I
2
C EEPROM entry can power up the port and set IO_SPEED field in
the SMAC0_DLOOP_CLK_SEL register to the correct value and power the port back up again.
3.5 Port Power Down
All of the Tsi578 RapidIO ports can be powered down to minimize power consumption when the port
is not required. However, port 0 has special power-down requirements that must be followed (see
“Special Conditions for Port 0 Power Down” on page 73 ).
When a port is powered down, some registers return 0 and all writes to these registers are ignored.
These values indicate that the RapidIO port is uninitialized. The following register types are read only
and return zero when a port is powered-down:
• RapidIO Physical Layer Registers (see “RapidIO Physical Layer Registers” )
• RapidIO Error Management Extension Registers (see “RapidIO Error Management Extension
Registers” )
• IDT-Specific RapidIO Registers (see “IDT-Specific RapidIO Registers” )
The following register types can be read and written to when a port is powered-down:
• “Serial Port Electrical Layer Registers” on page 361
• “Internal Switching Fabric (ISF) Registers”
• “I2C Registers” on page 415
• “Utility Unit Registers” on page 388
3.5.1 Default Configurations on Power Down
When a port is powered down, the port loses configuration information that is stored for that specific
port. For example, multicast settings and port write settings return to their default reset settings after a
port reset (port is powered down and back up). After port reset, there is no way to determine that the
configuration for a particular port is correct. The registers listed in
“Global Registers to Program after
Port Power Down” are imaged in every port but are accessed through one register address. Therefore,
the powering down of a port removes the image of that register in that port.
For example, if a port is shut down and then restored, the port write destinationID in that port is reset to
the default value. The port write destinationID must be re-written for the whole device after a port is
shut down and restored. Similarly, multicast settings for the entire device must be re-written when a
port is shut down and restored.
Both the “RapidIO Port x Error and Status CSR” on page 278 and “RapidIO Serial Port x
Control CSR” on page 281 registers return 0x00000001 when read instead of 0s.